The correct answer is - bones.
An osteologist is the the person that practices osteology, which is the scientific study of the bones. The osteology is a subdiscipline of the archaeology, anatomy, and anthropology, meaning that it is very important in multiple fields of study.
This osteology focuses on detailed study of the structure of the bones, teeth, the process of osification, skeletal elements, microbone morphology, and multiple other things connected to the bones.
All in all, if someone has a problem, a trauma related to the bones, an osteologist would be the right person to be called to help with it.